Why clever vegans supplement vitamin B12

Are you a vegan who doesn't supplement vitamin B12? I strongly urge you to reconsider or the consequences can be quite serious.

Everyone needs a constant source of B12, whatever their diet. Vegans should pay extra attention to this but just because you're eating someone else's flesh doesn't automatically mean you're safe.

Summary: Vitamin B12 deficiency is a real threat, especially for vegans. The ramifications can be severe and we should take precautions not to run the risk of becoming deficient. Luckily, it's very easy to avoid. Pop a cheap 500 Âµg B12 pill (cyanocobalamin) pill once per week or 50 Âµg once per day and you're good.

Vitamin B12 (or cobalamin) is vital for your brain and nervous system's function, as well as the formation of red blood cells. It has a key role in the metabolism of pretty much every cell of your body, in particular DNA synthesis, fatty acid, and amino acid metabolism3.

It works as a coenzyme â€“ enzymes uses it to do their job, changing one molecule into another.

No plant, fungi, or animal (humans included) are able to produce vitamin B12. Instead we have to rely on microbes for its synthesis. Bacteria in our colon can produce it but it happens so late in the intestines that we can't absorb it. Instead we need to find other sources.

Back in the days our food and water was a lot more contaminated than it is today. With the advent of clean water we've stopped many awful diseases from being spread but at the same time we've also removed reliable sources of vitamin B12.

People living close to animals in more unhygienic conditions proves this point.

One study4 mentions an indigenous Iranian tribe that still lived in the old ways. Eating practically no meat or dairy products these tribesmen still had perfect vitamin B12 levels, thanks to cross-contamination from the animals they lived with.

While Internet Rumoursâ„¢ would have you believe there are no vegan sources of vitamin B12, there are actually a few. Not all are created equal though and there are pitfalls to look out for!

The biggest danger of sourcing B12 from vegan food is that the vitamin they contain is inactive â€“ a pseudovitamin. This competes with active B12 for absorption, so it can actually speed up your deficiency.

Inactive pseudovitamin B12 can even be harmful for your nervous system5.

The best way to be sure if a source is active is to measure urinary methylmalonic acid (MMA)6 after eating. Basically looking at how much B12 you pee out to determine how much was absorbed.

Vegan, Korean children do just fine with nori as their only source of B1218 but that doesn't seem to be the case for German vegans19. From these studies, my guess is that 1) Korean nori contains more B12 and 2) Koreans by default eat a whole lot more nori than westerners.

Black trumpet and golden chanterelle (personal favorite!) was found to contain 1.0-2.5 Âµg vitamin B12 per 100 g of dried weight23. This can however vary a lot from farm to farm24 and is thus unreliable as a single source.

Commercially available shiitake mushrooms have been seen to contain even more B12 (~6 Âµg per 100 g of dried weight) but it too varied significantly between sources15.

Some typical symptoms include a loss of energy, numbness, tingling, blurred vision, sore tongue, reduce sensitivity to pain or pressure, confusion, poor memory, and hallucinations. There's no sure-tell sign of deficiency. If you suspect a problem â€“ go talk to a skilled medic.

Your liver can store up to 2500 Âµg vitamin B12 and depending on how well your intestines can re-absorb lost B12 (enterohepatic circulation) it can take anywhere from a couple of years to a couple of decades before you become deficient30.

Not all consumed B12 will be absorbed. In fact, the higher the dose the less efficient your absorption.

One systematic review28 came up with the following equation for how much we absorb:

LN(Absorption) = 0.7694 * LN(Intake) - 0.9614

If we plot that to a graph it'll look like this:

You absorb almost 2 Âµg from taking 8 Âµg but only just over 3 Âµg from taking 16 Âµg. It's almost linear but doesn't scale 1:1, so you'll have to take more than double to be able to absorb double.

The absorption also depends on the type of cobalamin you're eating. Protein-bound B12 is, for example, less well absorbed than crystalline B12 (cyanocobalamin)27333435.

Further, if you take the B12 just after eating it'll absorb only half as well36.

Those are the biggest variables for determining how much you absorb but there are more. Drinking alcohol, consuming huge quantities of vitamin C, calcium deficiency, pancreatitis, tapeworms, consuming pseudovitamin B12, etc. Lots of things that can screw with your absorption.

Smoking was thought to disturb the metabolism of vitamin B12 but when tested this doesn't seem to be the case27. There are other reasons you'd want to stay away from smoking though. ;)

You could use fortified foods like vegan milk or breakfast cereals to get your B12. Because they don't contain a whole lot, however, and since absorption decreases with higher doses, you'd have to consume it several times per day.

That'd work â€“ drink a big glass of fortified milk with each meal and snack and you should be good.

Personally I'm too undisciplined to make that work and instead I opt for B12 supplement pills.

We want to make up for the 1.4-5.1 Âµg lost per day and just to be sure we'll place ourselves in the far end and aim for 5 Âµg. Based on the above, we can run the numbers and come up with an estimate.

Here's my recommendation: take 50 Âµg per day OR 500 Âµg per week.

I'm not only undisciplined but also very forgetful (yeah, I'm quite the catch) and so I try to pop a 500 Âµg pill every few days, which results in just a little more than twice per week. This strategy also helps me refill my levels after traveling every now and then and forgetting the supplements at home.

Go with cyanocobalamin â€“ it's the cheapest and works just as well as other, more expensive forms of B1237 â€“ and take the supplement on an empty stomach to optimize absorption.

Don't listen to recommendations to inject B12, as it likely comes from ignorance of recent medical studies38. Oral supplementation is just as a effective3940 and modern medical science recommends that form4142.

B12 supplementation is the last carnist defense after fearmongering vegan protein deficiency.

The argument is that adding B12 to our diet makes it non-viable. But guess what?

The argument is that our vegan diet is non-viable because we have to add B12 supplement to it. But guess what? So does meat eaters! Only the farmers do it for them, just like fortified foods producers do for vegans.

Further, protein-bound B12 is much harder for our bodies to absorb and this gets worse with age.